“…These include the occurence of eye muscle palsies in the distribution of a specific cranial nerve, the fact that other cranial nerve involvement is of a lower motor neurone type, and the observation that anatomically adjacent motor and sensory pathways in the brain-stem are spared. In addition, the preponderance of pathological information supports a peripheral mechanism (Haymaker and Kernohan, 1949;Baker, 1943;Munch-Petersen and Reske-Nielsen, 1962). We must also consider the possibility that both peripheral and intramedullary mechanisms are operative, giving a mixed clinical picture.…”